The present invention relates to a machine for exercising muscles, effectively employable to train muscles of the upper part of the body, shoulders, back, chest, which for the sake of brevity, shall hereafter be indicated as "upper body muscles".
Normally, exercise machines for training upper body muscles are provided with a frame supporting a load unit, with counterweight or electrical, with which a user exchanges power by means of at least one lever with its fulcrum in the frame itself. Such a lever, normally realized with a tubular body, is gripped in its end position, in such a way as to maximize the physical lever arm, and hence power exchanges with the load unit. To render the gripping of the lever in the end position more comfortable, the lever is usually coated with a sleeve closed at one end, in such a way as to seal the lever itself. Such a sleeve is made of material presenting high friction coefficient in contact with the user's hands, in order to favor a secure grip on the lever, and prevent involuntary releases of the load, which in counterweight machines could be dangerous.
Normally, the end portion of the lever is oriented according to a determined position, in relation to the trajectory that needs to be effected to train a given muscle district. On the other hand, in order to allow users presenting different anthropometric measurements to assume the postures required for the execution of determined exercises, the sleeve presents a greater extension than the average palm of the human hand, so that even users with particularly long or short arms can safely activate the lever regardless of the point whereat they grip the sleeve.
Naturally, the gripping position will influence the angles scanned by the user's limbs, and the trajectories of the various junctions will be affected by this parameter. Therefore, on the same machine, different users will train muscle districts that are only approximately identical. In fact, the opportunity to train the target muscle district is reserved to a user whose anthropometric measurements are those adopted for the dimensioning of the machine.
Some designers have sought to reach trajectory uniformity and improve the ergonomics of the machines in question by adopting levers ending with annular handles, wherein the sleeve is mounted on a ring connected to the end of the lever so that it is able to rotate on an angle of determined amplitude. It should be noted that this does not solve the problem identified above, but only frees the user's wrist to assume the most conservative angle of the wrist and elbow joints.